Oxygen- and nitrogen-based free radicals are produced as a result of metabolism (oxidative phosphorylation), environmental stress, and the immune response. Exposure to excessive concentrations of radicals damages biomolecules, including DNA, proteins, and lipids. Persistent overproduction may cause oxidative stress to cells, ultimately resulting in or contributing to conditions such as inflammation, cancer, asthma, cardiovascular and neurological diseases, as well as age-related disorders. There is a need in the art for synthetic antioxidants for use in scavenging free radicals or reducing oxidative stress.